Over the past 30 years, the scope of Systems Neuroscience has expanded enormously. Functional brain imaging has provided the opportunity to study the neural mechanisms of complex cognitive functions in humans. Concurrently, powerful techniques such as optogenetics have made it possible to dissect neural circuits with unprecedented resolution. In parallel, computational approaches such as deep networks and Bayesian models are increasingly central to the field as a whole, putting a premium on advanced quantitative skills and literacy. Clearly Systems Neuroscience is now a trans-disciplinary field, integrating theoretical frameworks and techniques from molecular biology, neurophysiology, cognitive science, ethology, computer science, statistics, and more. In the face of this remarkable expansion, PhD programs face three challenges. First, although the body of knowledge relevant to Systems Neuroscience has increased in breadth and depth, students also face increased pressure to conduct research, publish, and get independent funding early in their career. Second, systems-level research is conducted in multiple departments and PhD programs. At Washington University, these include the PhD programs in Neuroscience, Psychology, and Biomedical Engineering. Yet, students coming from different disciplines often do not speak each other?s language. Third, a successful career in science requires a broad portfolio of professional skills ? writing papers and grant proposals, collaborating with colleagues with different scientific backgrounds, presenting results in scientific venues and to wider audiences, navigating the academic job market ? that exceed the normal coursework. The Cognitive, Computational and Systems Neuroscience (CCSN) pathway was developed in response to these challenges. CCSN is an elite pathway available for graduate students in years 3-4, with eligibility from multiple PhD programs relevant to Systems Neuroscience broadly defined. The emphasis of CCSN is on trans- disciplinary training and professional skills development. To access the pathway, students must complete (in years 1-2), three pre-requisite and foundational courses on systems neuroscience, cognitive science and animal behavior, and computational neuroscience. In year 3, CCSN students take two additional courses ? one providing foundational knowledge and hands-on training with advanced quantitative methods and data-science tools, and the other allowing them to develop a trans-disciplinary grant proposal ? which often becomes an actual NRSA application ? shaped by peer, instructor, and committee feedback. In year 4 (and throughout the pathway), CCSN students take part in multiple Career Development activities, including mentoring junior students, organizing scientific events, interacting with external speakers, participating in informal dinners with CCSN faculty, and taking part in community outreach. The CCSN pathway has existed for ~15 years and has a demonstrated history of remarkable success. Here we request funds for 5 fellowships. Contingent on the success of this application, Washington University will provide matching funds for an additional 5 slots.